They have sold a whopping 12.5million of the junior exec saloons in those 36 years — that’s an amazing figure for a premium priced car.

And already the new saloon is showing signs of being a big winner.

It went on sale in Scotland last weekend and Harry Fairbairn BMW in Giffnock and Irvine sold TWENTY in two days — raking in more than £500,000.

BMW aim to sell 21,000 3 Series’ a year in the UK.

It has become the ultimate driveway dream — even more common than the Ford Mondeo yet somehow remaining more special. In the UK, the BMW is in the top ten best-sellers every month, ahead of mainstream cars such as the Mondeo and Vauxhall Insignia.

One in three BMWs sold worldwide last year was a 3 Series, so it has to be spot-on. Which is why the latest 3 is more evolution than revolution.

The biggest departure from the old generation is that it’s much sleeker. The face is much more dynamic and powerful, with the double LED headlights linked into the trademark kidney grille.

Appropriately, given their Olympic link, the 3 Series is far more athletic. It has grown almost 10cms and has a lean profile like its big brother 5 Series.

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But the bulk has not affected its performance — it is 88lb lighter than the car it replaces. I’ve just had a first drive in Scotland of the new 3 and BMW have turned the handling and steering up to new levels of agility that get it even closer to its original tag of being the ultimate driving machine.

I tested two of the big sellers, the 320 diesel and the 328i petrol. They deliver totally different but equally impressive driving experiences.

The twin-turbo diesel is a motorway mile-muncher combining speed and economy — hitting 62mph in 7.5 seconds, 146mph top speed and 61mpg, so it is very much the perfect all-rounder.

There is also an Efficient Dynamics diesel with only slightly reduced performance but a claimed stonking eco 68.9mpg.

The 3litre twinturbo 328i is a beautiful mix of scintillating soundtrack and exhilarating performance.

Here 0-62mph takes just 5.9 seconds and top speed is 155mph while economy is still an acceptable 44mpg. All the new 3 Series manage to combine performance with improvements in emissions, from 109g/km in the Efficient Dynamics diesel to 186 for the 335i flagship.

There are also three petrol versions, starting with the 320i saloon, and four diesels opening with the 316d.

There will also be even more choice, with the new Sport, Modern and Luxury levels joining the ES, SE and M Sport.

But excellence comes at a price — from £24,880 for the 316d to £27,086 for the 320d and £29,060 for the 328i.

In typical BMW style, prices rise rapidly once you add on the extra kit. But this new 3 Series remains the premium saloon to beat. It’s pure gold.

What to look out for when buying a used BMW 3-series (2012-)

Nothing yet — no factory recalls and no pattern of problems emerging from owners — but we will report back if we hear anything.